That feature was turned off because if the first post in the thread is deleted, it takes all, which may not be desirable. You can just PM the moderator for the forum which has the post you want removed. Best to give him the url to the post. In the mean time, or if it's a useful thread which should not be deleted, the best thing to do is replace the text with a smiley, a frowny or a dot, as you did.
If you wish to change a title, that also requires a moderator's intervention.